When someone is re-elected it should be as austere as a courthouse wedding. The Chief Justice slaps you on the back and says get back to work.

I'm not sure which is worse, taxpayer money, or corporate donors paying for any part of it.

But this is the highest office in the land so some extravagance seems ok to me. It might be neither taxpayer money nor corporate donors paying for the lunch or most of the celebration. Instead individual attendees pay hefty ticket prices. This says it costs $1,475 for a ticket to the inaugural ball: http://inauguraltickets.com/